1. Field of the Invention:
The present invention relates to a magnetic tape cassette such as a video tape cassette.
2. Description of the Prior Art:
FIG. 1 and FIG. 2 are schematic views of the conventional magnetic tape cassette wherein reels (4), (5) holding a wound magnetic tape (3) are positioned in the casing comprising an upper half casing (1) and a lower half casing (2) and tape guides (8), (9) supported by guide poles (6), (7), a tape pad (10) and a guide pole (11) are placed in the running path of the magnetic tape (3) between the reels (4), (5) so that the magnetic tape (3) can continuously run in contact with the tape guides (8), (9), the tape pad (10) and the guide pole (11) to be wound on the reel.
In the conventional device, the guide poles (6), (7) and (11) are respectively fixed by forcibly inserting one end into each of axial holes (12), (13), (14) previously formed in the surface of the upper half casing (1) or the lower half casing (2). The axial holes (12) to (14) of the conventional device are circular in cross-sectional shape as shown in an enlarged view of FIG. 3 and the inner diameters of the axial holes (12) to (14) correspond to the outer diameters of the guide poles (6), (7), (11) in order to prevent a loose fit of the guide poles (6), (7), (11) in the axial holes (12) to (14). It is necessary to forcibly insert the guide poles (6), (7), (11) into the holes (12) to (14) after applying a lubricant such as grease to the surface of one end of the guide poles (6), (7), (11). However, the application of the grease completely closes the gap between the inner wall of the axial holes (12) to (14) and the outer surface of the guide poles (6), (7), (11) when forcibly inserting the guide poles so that air in the holes (12) to (14) can not be released and remains compressed in the bottom of the axial holes. This causes the guide poles (6), (7), (11) to lift up after the forcible insertion due to the repulsive force of the compressed air thus resulting in the prevention of normal movement of the magnetic tape.